A senior researcher at GNS Science is using a novel test that can verify if vegetables in the supermarket have been grown organically.
Karyne Rogers of GNS Science’s Stable Isotope Laboratory in Lower Hutt said the method was an inexpensive way to verify the organic status of vegetables by distinguishing between vegetables grown with organic or industrially made fertilisers.
A criteria in growing organic vegetables is that only organic fertiliser, usually animal manure, is used. As vegetables grow, they incorporate nitrogen from the fertiliser and it is this nitrogen which is analysed. The nitrogen isotope signatures of animal manure and industrial fertiliser are quite different.
“It’s an independent check on the growing regime. As far as I am aware, this is the first simple reliable test for organic vegetables in New Zealand,” Dr Rogers said. “Consumers need independent checks for produce that cost significantly more because of its label.”
Clients can obtain results within 10 days of submitting samples, and the test can be done at any stage during vegetable growth. This method can also determine if vegetables are grown hydroponically, or naturally in soil.
A similar isotope technique using carbon can be used to determine if vegetables, such as tomatoes, have been grown in a greenhouse heated by fossil fuels.
Dr Rogers said these new tests were an extension of the food testing that the Stable Isotope Laboratory has been doing for the past 12 years.
“Since 1996 we have been testing orange juice for the beverage industry to determine if sugar or tap water has been added.”
“We also offer a test for the honey industry to determine if bees have been fed sugar or if glucose has been added to increase the volume of the honey.”
Dr Rogers’ team is developing isotope-based tests that would determine if produce labelled “NZ Grown” was in fact grown in New Zealand.
Isotope analysis techniques offered the food industry a quick and reliable way to boost the confidence in labelling, Dr Rogers said.
More links with interviews here:
Science Story: NZ scientists go vegetable
National Radio
(Audio - duration 3'55")
New Zealand scientists have for the first time found a way to tell if an organic vegetable is really organic.
Checkpoint: 2008/08/09
How to test your vegetables for natural or industrial fertilisers.
Television New Zealand
(Video duration 3'02")
Senior researcher at GNS Science, Karyne Rogers, explains a test she's developed that can establish whether a vegetable has been grown with natural or industrial fertilisers.
Breakfast Television TV1: 2008/08/09
Abstract:
Nitrogen Isotopes as a Screening Tool To Determine the Growing Regimen of Some Organic and Nonorganic Supermarket Produce from New Zealand
KARYNE M. ROGERS†
National Isotope Centre, GNS Science, 30 Gracefield Road, Lower Hutt, New Zealand
An isotopic study was performed on nine varieties of organically and conventionally grown vegetables from an organic food market and a chain supermarket in New Zealand. The main aim of the study was to assess the applicability of stable nitrogen isotopes as a screening tool to differentiate between organic and conventional growing conditions of various vegetable types sampled directly off supermarket shelves. This could be further used as the basis of a simple authentication tool to detect noncompliant organic farming practices and false labeling of organic produce. In this study, nitrogen isotopes are found to be an excellent way of identifying faster growing organic vegetables (maturity time to harvest of 80 days), more information would be required to understand isotopic variations and fractionation effects between vegetables and soil over time as the technique does not discriminate organic from conventional regimens for these vegetables with as much certainty.
KEYWORDS: Nitrogen; isotope; organic; manure; fertilizer; vegetable; carbon; ä15N; ä13C.
http://pubs.acs.org/cgi-bin/abstract.cgi/jafcau/2008/56/i11/abs/jf800797w.html
